This invention relates to processes for making nylon foam and to the nylon foam produced by the processes.
Nylon foam has typically been produced by the inclusion of a blowing agent during extrusion. Typical extrusion processes employ vented extruders. Glass fiber reinforcement is almost always used in order to achieve the hot strength necessary to produce nylon foam of even moderately low densities. Owens et al, U.S. Pat. Nos. 3,668,274 and 3,796,771 teach a multi-phase amine-reactive carboxylic acid-containing polymer which is graftable to the amine groups of a polycarbonamide and to improve the impact resistance of the polycarbonamide as well as the hot strength to render to polymer extrudable, blow moldable, and injection moldable.
The present invention relates to an improvement of the Owens et al system wherein polycarbonamide foam is produced.